"Paycor told me that my credits for sick leave would total $1336.42."

The Social Security component is the .062. The Medicare component is the .0145.

"So it looks like we will be late now and owe a few bucks. Why did they do this?"

They, who? Why doesn't your payroll provider do your forms?

"Now after doing the 941"

Did you need the IRS instructions:

https://www.irs.gov/newsroom/covid-19-related-tax-credits-for-paid-leave-provided-by-small-and-midsi...

"I hate to have a penalty."

You've got time to make any payment still due for 1st quarter. Honestly, I have not read up on the 2021 payroll stipulation, but isn't that Employee Paid? If you have a payroll provider, then I assume you are not using EasyAcct to do the payroll? The other programs in use in this community are income tax preparation programs ProConnect, ProSeries, and Lacerte.

If you are not using EasyAcct, ProSeries, ProConnect or Lacerte, you are in the wrong peer user community on the internet. We can't help with any other software. Sorry.

Have you called Paycor? I've caught a lot of payroll provider errors.